Constantine Mavrocordatos (Greek: Κωνσταντίνος Μαυροκορδάτος, Romanian: Constantin Mavrocordat; February 27, 1711 – November 23, 1769) was a Greek noble who served as Prince of Wallachia and Prince of Moldavia at several intervals. As a ruler he issued reforms in the laws of each of the two Danubian Principalities, ensuring a more adequate taxation and a series of measures amounting to the emancipation of serfs.

He ruled Moldavia four times from 1733 to 1735, from 1741 to 1743, from 1748 to 1749 and in 1769. He entered a personal rivalry with Grigore II Ghica; Ioan Neculce noted "Constantin-Voivode went lengths to replace Grigorie-Voivode's rule in Wallachia (...)", and subsequently "(...) as soon as they were seated on their thrones [during one of Constantine's rules in Wallachia], they began to quarrell and to report each other to the Porte without concealment".

His reigns were distinguished by numerous tentative reforms in the fiscal and administrative systems, partly influenced by those of the Habsburg Monarchy during their presence in Oltenia; initiated in Wallachia, they were to be applied consistently in Moldavia as well.

He was responsible for the annulment of several indirect taxes, such as the văcărit (the taxation per head of cattle), and replaced them with a single tax of 10 löwenthaler, which could be paid in four annual "quarters". Faced with the exodus of serfs to neighbouring Transylvania, Mavrocordatos allowed them freedom of movement from one boyar estate to another, in exchange for a 10 löwenthaler fee (the effective abolition of serfdom: 1746 in Wallachia, 1749 in Moldavia).[1] At the same time, he imposed a quitrent, a 12 days-corvée, and allowed the boyars a retinue of serfs (scutelnici) that were exempted from the state tax (and owed taxes only to their liege lord).[2] On these reforms as experienced in Moldavia, Neculce expressed his view that "were he not to have this heavy retinue of his father's, with all those insatiable people, and were he not prone on removing his cousin Grigore-Voivode from Wallachia, there would not have been such plunder in the country".

The prince attempted to impose a degree of centralism in the face of boyar privilege, and, despite boyar protests, created an administration which relied on a more professional, salarized apparatus, consisting of ispravnici he himself appointed to office, and who could act as judges; he also merged the traditional personal treasury of princes with that of the Wallachian administrative body, and decided to deny boyar title to families whose members no longer held official appointments.[3] In 1761, due to the reforms' effects, the Ban of Oltenia moved his seat from Craiova to Bucharest, leaving the region to be ruled by a kaymakam.[4]

Mavrocordatos was wounded and taken prisoner by the Russian troops of Catherine II, after his resistance in Galaţi during the Fifth Russo-Turkish War, on November 5, 1769. He was taken to Iaşi where he died in captivity. Despite their attempts to have the reforms overturned, boyars had to deal with their effects, as successive rulers confirmed the laws' scope.[5]